The bodies of Hamas fighters lay on the streets of Kfar Aza, a kibbutz close to the border with Gaza, as Israeli soldiers went door-to-door to secure it days after it was overrun. They were among the 1,500 dead militants Israel says it found inside its border after Hamas’ surprise raid from Gaza.

Among the grim, extraordinary numbers that tell the story of the militants’ attack on Israel, that one, in particular, has dumbfounded experts. Itraises the question of how large Hamas’ total fighting force is — and what a bloody, close-quarters ground offensive in Gaza might look like